The overall goal of this Mentored Patient-Oriented Research Career Award is to provide the applicant Development with the necessary tools to become an independent investigator in aging and Alzheimer's disease, through the conduct of an epidemiologic study of risk factors for incident Alzheimer's disease, change in cognitive and motor function, and risk of death. Prior work suggesting that Alzheimer's disease and parkinsonian signs are strongly related, raises the possibility of shared etiopathogenesis. We propose to examine oxidative stress as a risk factor for incident Alzheimer's disease, change in cognitive function and progression of parkinsonian signs, and risk of death. The proposed study will take advantage of frozen serum specimens from 900 persons without dementia participating in the Religious Orders Study, an ongoing epidemiologic study of aging and Alzheimer's disease, and longitudinal clinical data from annual structured clinical evaluations. There are already approximately 150 cases of incident disease and 200 deaths. In addition to this focused, structured, and timely research project, the career development plans include structured mentoring in a highly successful, multidisciplinary environment, and a program of formal course work that will lead to a Masters of Science in Clinical Research.